Testing relative evolutionary rates and estimating divergence times among six genera of Rhizophoraceae using cpDNA and nrDNA sequences

The molecular phylogenetic trees of 10 species representing 6 genera of the family Rhizophoraceae have been constructed using the sequences of chloroplast genesmatK andrbcL as well as the ITS regions of nuclear ribosomal DNA. Relative-rate tests between lineages in these phylogenetic trees have been performed. On the basis of the results of the relative-rate tests and related molecular evolutionary rate data, the divergence times between the lineages are estimated as follows: (i) the first divergence time in these genera is 132.25 million years ago (mya); (ii) the average divergence time between two tribes, i.e. inland Legnotideae (exceptCarallia brachiata) and mangrove Rhizophoreae, is 64.13 mya; and (iii) the average divergence time between two inland species,C. garciniaefolia andC. pectinifolia, is 19.92 mya.